Go to settings -> Security -> Screen Lock
You want to change the screen lock options to swipe or pattern. All options (i.e. Swipe, motion, face unlock, pattern etc) are disabled.
Scroll further down the security settings to Device Administration. Select Device Administrators . If you have anything listed here, you can click on them and see what you have granted. It’s most likely an app that has admin access, typically the standard Email App from Samsung. Deactivate and go back to your lock screen options again.